Method of alloying magnesium with manganese



Patented Nov. 4, i943 starts a is m'rnon or ALLOYING MAGNESIUM wrrn MANGANESE Charles E. Nelson and George F; Gunn, Midland,

Mich, assignors to The Dow Chemical Company, Midland, Micln, a corporation of Michithe presence of a flux consisting of a fused mixture of inorganic compounds, to prevent burning. The flux may be lighter than the alloy and form a crust over the surface of the molten metal, or it may be of such density that a part only of the flux remains over the metal as a film, the main body of the flux being beneath the metal. In( some instances the flux is chosen for its ability to form a thin skin over apart of the metal, leaving a portion of the surface uncovered. v

It is also well known practice to alloy magnesium with manganese by introducing .an an-' hydrous reducible manganese compound into the molten magnesium. The commonest reducible manganese compound employed for alloying manganese with magnesium is manganous chloride. When manganous chloride is added to,

molten magnesium, or magnesium base alloy, there is an almost instantaneous reduction to metallic manganese, accompanied by the formation of magnesium chloride in amount equivalent to the chlorine introduced in the manganese chloride. The magnesium chloride so formed becomes part of the inorganic flux system, thereby changing the composition of the said system. The flux cannot, therefore, be re-used indefinitely in the same type of operation because of its changed composition, and, even in the same limit,

it no longer serves its original function to the desiredextent. When starting operation in a clean melting pot it is particularly undesirable to use as a flux a mixture already containing the magnesium analog of the manganese compound to be employed, though this has been standard practice, 7

It is, accordingly, among the objects'of the present invention to provide a method of opera-' tion, particularly of initial operation, in which magnesium or a magnesium base alloy is melted ganese compound, in such proportion that, after reaction between the magnesium and the manganese compound, the resulting flux has the desired characteristics. Another object is to providecomposi'tions of matter containing reducible manganese compounds, to be melted with magnesium or its alloys such that, after the manganese compound has reacted with the magnesium, there remains a flux having the desired characteristics. Y It has now been found that the foregoing an related objects may be attained by initiating operation in a clean melting pot or other suitable alloying vessel employing a charge of magnesium or magnesium base alloy and a fiux of inorganic compounds including a reducible manganese compound but free from the magnesium analog of said reducible manganese compound, the flux ingredients being in a suitable proportion as will be illustrated hereinafter, so that after reaction between the magnesium and the manganese compound there is formed a suflicient amount of the magnesium compound to contribute to the inorganic mixture the desired and Well known flum'ng characteristics normally sought in protective fluxes.

More specifically, the inventionis a method of alloying magnesium or a magnesium base alloy with manganese, in which molten magnesium is to be protected with a final inorganic flux containing a particular magnesium compound, which comprises placing solid magnesium or magnesium base alloy in a clean melting vessel, in contact with an original flux (to give temporary protection) differing from the desired final flux by being free froln significant amounts of the desired final magnesium compound and by containing the reducible manganese analog of the said magnesium compound desired in the final flux, in amount to yield the requisite amount of manganese and equivalent to the desired amount of said magnesium compound in the final flux, together with other flux ingredients in the proportion relative to one another in which they should appear in the final flux, and heating the magnesium and original flux at least to the melting point of the magnesium, thereby to reduce the manganese compound and to form an equivalent weight of itsmagnesium analog, producing the desired final flux and a manganese-conln the presence of a reducible manganese compound together with inorganic flux ingredients,

taining magnesium alloy protected. thereby.

The term originalflux herein employed refers to the mixture of inorganic compounds including a reducible manganese compound lnitially charged into an empty and substantially clean melting pot or equivalent vessel along with the magnesium or magnesium base alloy to which it is desired to add manganese as an alloying ingredients. The term "final fiux" refers to the inorganic compound mixture present as flux after reaction between the magnesium and the manganese compound, and in the present specification it is understood that the final fiux always contains the magnesium analog of the manganese compound employed in the original flux. The term magnesium analog of the manganese compound employed" can best be defined by means of example: Thus, magnesium oxide'is Example 1 g I l Magnesium is melted in a clean pot, i. e., one containing no fiux remaining from previous operations, in the presence of an original fiux consisting of Per cent Manganous chloride 38 Potassium chloride 48 Calcium fluoride 5 Barium chloride 9 When the magnesium reaches the melting point it reacts instantly with the manganous chloride liberating an equivalent amount of magnesium chloride. The so-formed manganese-containing alloy floats on the main body of fiux with but a thin film a: fiux over its surface. The final fiux has the approximate composition Per cent Potassium chloride 53 Calcium fluoride Barium chloride l Magnesium chloride 32 The foregoing final fiuxing composition is one which has long been used satisfactorily for the protection of molten magnesium and its alloys.

Example 2 In a clean melting pot was placed a magnesium-aluminum alloy containing more than the desired amount of-iron as an impurity. This alloy was melted in the presence of an original fiux containing sufilcient manganese compound to settle the iron and to alloy with the magnesium. The original flux employed consisted of Per cent .6

Manganous chloride 12 Potassium chloride 23 Calcium fluoride 2.5 Barium chloride 2.5

The iron was settled in the customary manner and the final flux had fiuxing characteristics very similar to those of the final flux described with respect to Example 1, though containing .somewhat more magnesium chloride and less an original fiux consisting of potassium chloride, having an approximate analysis of Magnesium chloride 66 Example3 In a manner similar to that described in the preceding examples magnesium was melted with H I Per cent Manganous chloride 64 Sodium chloride 36 in quantity sufiicient to produce 1 per cent of manganese based on "the weight of the magnesium present. The final flux, consisting of Per cent Sodium chloride 44 Magnesium chloride 56 is a well known flux for magnesium metals and behaved in its normal manner, settling to the bottom of the vessel but leaving a film of fiux over the top of the molten metal.

Example 4 A mass of magnesium was placed in a clean melting pot along with a small amount of an original fiux consisting of Per cent Manganous chloride '70 Calcium fluoride 15 Magnesium oxide 15 Percent Calcium fluoride l8 Magnesiumoxide 18 M nesium chloride i; 54

Another original flux which has been found to give a satisfactory final flux with normal flux characteristics is one consisting of Per cent Manganous chloride 30 Potassium chloride 35 Lithium chloride 30 Potassium fluoride 5 The corresponding final flux is Per cent Magnesium chloride 25 Potassium chloride 38 Lithium chloride 32 Potassium fluoride 5 Another suitable original fiux is I Per cent Potassium chloride 15 Lithium chloride 15 Potassium fluoride l0 Manganous oxide; 60

The corresponding final fiuxis V Per cent Potassium chloride 20 Lithium chloride 20 Potassium fluoride 14 Magnesium oxide 46 aaeaeoe 3 A fluid final flux is obtained when using as the original flux a mixture of Per cent Calcium chloride 50 Calcium fluoride l Barium fluoride .20 Manganous fluoride The final fiux is Per cent Calcium chloride 54 10 Calcium fluoride l1 Barium fluoride 21 Magnesium fluoride 14 The foregoing examples have illustrated orig- 5 inal fiux compositions wherein the manganese compound has been manganous chloride, manganous fluoride, and manganous. oxide. The resulting final fluxes have been or various types representing the range of fiuxing properties de- 2 sired for the difierent types of high temperature operations normally carried out on molten magnesium and its alloys. Numerous other original fluxes may be made up, according to the invention, in a proportion to yield known and desired The manner in'which thismay be done will be understood. readily by a skilledchemist or metallurgistfrom the description, herein contained.

It is observed that the present invention is so compound were added to themetal through any .of the customary final fluxes, the amount of magnesium compound formed normally adds to the fiux system enough magnesium compound to alter materially the fusion characteristics of the fiux.

When, however, the manganese compound is 5 added in an original flux of the herein described type this fiux gives adequate protectionuntil the metal is melted, at which time it promptly reacts with the manganese compound, liberating enough magnesium compound to give to the inorganic flux mixture well recognized fiuxing characteristics.

l. A method of alloying magnesium with manganese, in which molten magnesium is to be protected with a final inorganic fiux containing a magnesium compound, which comprises placing solid magnesium in a clean melting vessel, in contact with an original flux difiering from the desired final flux by being free of significant amounts of the desired final magnesium com 0 pound and by containing the reducible manganese analog of the magnesium compound desired in the final fiux, in amount to yield the requisite amount of manganese, and equivalent to the desired amount of analogous magnesium compound in the final flux, together with other fiux ingredients in the proportion relative to one another in which they should appear in the final fiux, and heating the magnesium and original flux at least to the melting point of the magnesium, thereby to reduce the manganese compound and to form an equivalent weight of its magnesium analog, producing the desired final fiux and a manganese-containing magnesium alloy protected thereby.

' 2. A method of alloying magnesium with manganese, in which molten magnesium is to be protected with a final inorganic flux containing magnesium chloride, which comprises placing solid magnesium in a clean melting vessel, in

contact with an original flux differing from the' desired final fiux by being free from significant amounts of magnesium chloride and by containing manganese chloride in amount to yield the requisite amount of manganese, and equivalent to the desired amount of magnesium chloride in the final flux, together with other flux ingredicuts in the proportion relative to one another in which they should appear in the final flux, and heating the magnesium and original flux at least to the melting point of the magnesium, thereby to reducethe manganese chloride and to form an equivalent weight of magnesium chloride, producingthe desired final flux and a manganese- 0 containing magnesium alloy protected thereby.

3. A method of alloying magnesium with manganese, in which molten magnesium is to be protected' with a final inorganic flux containing magnesium fluoride, which comprises placing solid magnesium in a clean melting vessel, in contact with an original flux difiering from the desired final flux by being free from significant amounts of magnesium fluoride and by containing manganese fluoride in amount to yield the requisite amount of manganese, and equivalent to the desired amount of magnesium fluoride in the final flux, together with other flux ingredients in the proportion relative to one another in which they should appear in the final flux, and heating the 5 magnesium and originalfiux at least to themelting point of the magnesium, thereby to reduce the manganese fluoride and to form an equivalent weight of magnesium fluoride, producing the desired final fiux and a manganese-containing magnesium alloy protected thereby.

4. A method of alloying magnesium with man-,

ganese, in which molten magnesium is to be protected with a final inorganic fiux containing magnesium oxide, which comprises placing solid magnesium in a clean melting vessel, in contact with an original fiux differing from the desired final flux by being free from significant amounts of magnesium oxide and by containing manganese oxide in amount to yield the requisite amount of manganese, and equivalent to the desired amount of magnesium oxide in the final flux, together with other flux ingredients in the proportion relative to one another in which they should appear in the final flux, and heating the magnesium and original flux at least to the melting point of the magnesium, thereby to reduce the manganese oxide and to form an equivalent weight of magnesium omde, producing the desired final flux and a manganese-containing magnesium alloy protected thereby.

5. A method of alloying magnesium with manganese, in which molten magnesium is to be protected with a final fiux consisting of about 53 per cent potassium chloride, about 5 per cent calcium fluoride, about 10 per cent barium chloride,

and about 32 per cent magnesium chloride, which comprises placing olid magnesium in a clean melting vessel, in contact with an original fiux consisting of about 48 per cent potassium chloride, about 5 per cent calcium fluoride, about 9 per cent barium chloride, and about 38 per cent manganous chloride, and heating the magnesium and original flux at least to the melting point of the magnesium, thereby to reduce the man- 7 ganous chloride and to form an equivalent weight of magnesium chloride, producing the desired flnal flux and a magnesium-manganese alloy protected thereby.

6. A method or alloying magnesium with manganese, in which molten magnesium is to be protected with a final flux consisting of about 54 per cent'calcium chloride, about 11 per cent calcium fluoride, about 21 per cent barium fluoride, and about 14 per cent magnesium fluoride, which comprises placing solid magnesium in a clean 0 melting vessel, in contact with an original flux consisting of about 50 per cent calcium chloride,

fluoride and to form an equivalent weight of magnesium fluoride, producing the desired flnal flux and a magnesium-manganese alloy protected thereby.

CHARLES E. NELSON. GEORGE F. GUNN. 

